Thermostatic switch



Feb. 20, 1962 B. STEVENS 3,022,405

THEIRMOSTATIC SWITCH Filed May 28, 1959 2 Sheets-Sheet 2 INVENTOR. 88ml. 1. .STfVfMS fl/S ATTORI/[V United States Patent Filed May 23, 1959, Ser. No. 816,544 3 Claims. or. 200-138 This invention relates to thermostatic switches and more particularly to thermostatic switches of the snapaction type.

It is a primary object of this invention to provide an improved thermostatic switch having improved operating characteristics and simplicity of construction.

Another object of this invention is to provide a thermostatic switch that includes a base to which is attached a bimetal member and a flexible contact carrying member, there being a C-shaped spring connected between the bimetal member and the contact carrying member. The C-shaped spring preferably has an opening that receives a projection on the bimetal member and has a reversely bent portion that engages a projection on the contact carrying member.

Still another object of this invention is to provide a thermostatic switch wherein both the make and break temperatures of the switch are adjustable.

A further object of this invention is to provide a switch wherein the fixed contact thereofis supported by a plate member that forms a part of a bracket assembly that also includes a male connector terminal.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein preferred embodiments of the invention are clearly shown.

In the drawings:

FIGURE 1 is a top view of a thermostatic switch made in accordance with this invention.

FIGURE 2 is a top View of a thermostatic switch made in accordance with this invention with the cover thereof removed.

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2.

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 3.

FIGURE 5 is an exploded view of the thermostatic switch of this invention.

Referring now to the drawings, it i seen that the switch of this invention comprises a base member designated in its entirety by reference numeral 10. This base memher is formed of any suitable moldable insulating material. The base member at the left end thereof supports a plurality of stacked elements that form the operating parts of the switch. Thus, as is clearly apparent from FIGURES 3 and 5, the base member supports terminal members 12 and 14, a strut member 16, an insulator member 18, a bimetal actuator member 20, an insulator member 22, and a pair of steel washers designated by reference numeral 24. These elements are all held in stacked relationship by a rivet 26 which is headed over as at 28 in order to hold the various elements in tight engagement with each other.

The terminal member 12 has a configuration illustrated in FIGURE 5 and is provided with a male terminal portion 13 that is adapted to be received within a female terminal. The terminal member 14 is comprised of sections 28, 3t), 32, 34 and 36. It is seen that portions 28 and 30 are located at right angles to each other and that portion 32 forms a male terminal portion that is adapted to be fitted within a female connector. The portion 34 extends upwardly from portion 28 and merges into a platform section 36 which is disposed at right angles to the section 34. The platform section 36 has a threaded opening 38 that receives a threaded adjusting member designated by reference numeral 40. The adjusting member carries an electrical contact 41. The section 36 has another opening 42 which receives one end 44 of a clip designated by reference numeral 46. The clip is formed of spring steel and it is observed that the portion 48 thereof engages the adjusting screw 40 to hold the adjusting screw in its adjusted position.

The strut member 16 is formed of flexible copper material or the like and has a central opening designated by reference numeral 50. This strut member carries an electrical contact designated by reference numeral 52 that at times engages the contact 41 on the adjusting screw 40. The contact 52 thus becomes the movable contact of the electric switch. The strut member 16 has a generally V-shaped projection 54 which is engaged by one end of a generally C-shaped spring designated by reference numeral 56.

The bimetallic member 20 has a configuration as shown in FIGURES 3 and 5 and is formed of any suitable bimetallic material that will deflect upon changes in temperature. The bimetallic member 20 is constructed to deflect downwardly with decreasing air temperature and to deflect upwardly with increasing air temperature. The bimetallic member 20 has a projecting portion 55 that is bordered by edges 58 of the member.

The spring metal member designated by reference numeral 56 as noted hereinbefore is generally C-shaped and has an opening 69 which receives the projection 55 of bimetallic member 20. The spring metal member 56 has a reversely bent portion designated by reference numeral 62 which contacts the tip of V-shaped projection 54 formed on strut member 16. The spring member 56 is thus interposed between the end of bimetallic member 20 and strut member 16 and has a point contact with the end of V-shaped member 54. When the spring is so assembled, the spring contacts the edges designated by reference numeral 58 of the bimetallic member 20.

The electric switch of this invention is provided with a cover member generally designated by reference numeral 64 and having openings 66 formed in the top side thereof. The cover member has end openings which snap over the flange portions 68 of base member 10. The cover also has side openings 67 and 70. The base member it) has a threaded opening designated by reference numeral 72 that receives a threaded member designated by reference numeral 74. As will become more readily apparent hereinafter, the adjusting member 74 is operative to adjust the make temperature of the thermostatic switch.

Assuming now that the switch is in the position of FIGURE 3 with the contact 52 engaging the top edge of adjusting screw 74, the bimetallic member 20 will move downwardly upon a decrease in air temperature. When the end of the bimetallic member 20 moves downwardly sufliciently to pass through the opening 56 of the strut member 16, the spring 56 causes the strut member 16 to deflect upward suddenly causing contact to be made between the electrical contacts 52 and 41. This will eomplete an electrical circuit between male terminal ends 13 and 32 via terminal member 12, strut member 16, contacts 52 and 41, through adjusting screw 40 and thence to platform portion 36 and through sections 34, 28 and 30 to the terminal portion 32. If the temperature of the air now increases suificiently to cause an upward deflection of the end of bimetallic member 20, the strut member 16 is forced downwardly with a snap action to cause an engagement of contact member 52 with adjusting screw 74. The circuit between male terminal portions 13 and 32 will then be broken and the switch will be in the position illustrated in FIGURE 3. It is to be observed that both the making movement and breaking movement of sesame the switch take place with a snap-action. It has been found that this switch provides very accurate control due to the specific manner in which the G-spring 56 is connected with bimetallic member 20 and strut member 16. Thus, the provision of the opening 60 that receives projection 55 and the provision of the reversely bent portion 62 that engages the end of \'-shaped member 54 pr rides for accurate snap-action of the switch.

it will be appreciated that both the make and break temperature of the switch of this invention are adjustable. Thus, the make temperature of the switch illustrated in the drawings is adjustable by rotation of adjusing screw '74. The break temperature of the switch on the other hand is adjustable by rotation of adjusting screw 40. With this arrangement, the switch may be caused to be operated over a relatively narrow range of temperature values and is highly versatile in its application.

While the embodiments of the invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A snap acting thermally actuated electric switch comprising, a base member formed of electric insulating material, a combined terminal and contact support formed of a unitary piece of metal material resting on and secured to said base member, said combined terminal and contact support having a first male terminal portion projecting from said base, a supporting section secured to said base and extending substantially normal to said male terminal portion, a portion located opposite said male terminal portion and extending upwardly from said supporting section and a contact supporting section extending from said upwardly extending portion and substantially normal thereto, said contact supporting section overlying said base member and carrying an electrical contact, a second male terminal extending substantially parallel to said first male terminal portion of said combined a terminal and contact support, a bimetallic member, a strut member, a rivet securing said bimetallic member, said strut member and said second male terminal member to said base member in cantilever fashion, said strut member and bimetallic member extending in the same direction and said strut member being longer than said bimetallic member and having a central opening through which said bimetallic member may pass with a snap action, a spring metal member connected between said strut member and said bimetallic member, means electrically insulating said bimetallic member from said strut member, and an electric contact carried by said strut member cooperating with the contact carried by the contact supporting section of said combined terminal and contact support.

2. The electric switch according to claim 1 wherein the spring metal member has a generally C-shaped configuration and has a reversely bent section engaging a V-shaped projection on said strut member that is located on the longitudinal axis of said strut member.

3. The electric switch according to claim 1 wherein a cover member is fitted to said base member having air inlet and air outlet openings formed in more than one wall of said cover member for the passage of air past said bimetallic member.

References Cited in the file of this patent UNITED STATES PATENTS 1,875,699 Brady Sept. 6, 1932 2,068,374 Carlson Jan. 19, 1937 2,477,408 Gross July 26, 1949 2,667,612 Lucas Jan. 26, 1954 2,697,164 Knapp et al. Dec. 14, 195A 2,816,195 Holmes Dec. 10, 1957 2,820,870 Moksu Jan. 21, 1958 2,906,840 Ulanet Sept. 29, 1959 

